Physical Description

Tupaia came from the Malay word “tupai,” meaning squirrel. This is fitting since common tree shrews, with their pointy snouts and bushy tails, bear a resemblance to squirrels. However, T. glis can be distinguished from squirrels by the absence of long whiskers. The genus Tupaia is known to encompass species with the least specialized characteristics of all tree shrews. This is in part due to the semi-terrestrial lifestyles of species in this genus. Although arboreal tree shrews tend to have a relatively small body size with a short snout, a long tail, eyes facing forward, and poorly developed claws, terrestrial tree shrews have a larger body size with a long snout, short tail, eyes oriented laterally and well-developed claws. Tupaia glis has characteristics that are intermediate to these extremes.

Tupaia glis has an average body weight of 142 grams, a head and body length of 19.5 cm and tail length of 16.5 cm. Its pelage is dense and dark brown on the dorsal region of the body and orange-rufous ventrally. A pale shoulder stripe is present. Multiple subspecies and races are designated at decreasing latitude in the Malaysia Peninsula; these are based on progressive lightening of the dorsal color. There is no sexual dimorphism present in common tree shrews.

Reproduction

For the most part, common tree shrews are monogamous. The union between females and males seems to be prominent and permanent as revealed by scent marking between the pair and sharing of the same territory. However, monogamy in this species may be the result of some unexplained ecological constraints.

An exception to strict monogmamy has been noted in Singapore, where a polygynous mating system occurs. In this case, a male's home range may encompass the home ranges of several females, leading him to a polygynous mating system. Home ranges of like-sexxed individuals do not overlap.

Although T. glis has a year round breeding season in the wild, breeding has been shown to peak between February and June on the Malaysian Peninsula. The finding that T. glis females experience estrus during December followed by another estrus, with births occurring in February and April, further suggests a February to June breeding peak. Kawamichi and Kawamichi (1982) reported that T. glis is reproductively inactive from August to November.

The estrous cycles last anywhere from 8 to 39 days and gestation has been reported to extended from 40 to 52 days. Reproduction in T. glis is characterized by delayed implantation of the blastocyst despite the female being in estrus during the interbirth phase. This maximizes the number of offspring that a female can produce in a lifetime.

Common tree shrews are unique in their basic parental care. An unusual component is the construction of two separate nests, one for the parents to sleep in and another where the offspring are kept. Nests are often made by the male in holes, trees, under roots, or in hollow bamboo, and are filled with dry leaves.

Although it is unusual among mammals for a male to build the nest for the young, even more extraordinary is the small amount of time the mother spends with her offspring! Female common tree shrews visit their young every 48 hours to nurse them for 10 to 15 minutes. In that time, an offspring will receive 5 to 15 grams of milk that is high in protein and low in carbohydrates. The maternal care does not include any toilet care. The total average amount of time that a female spends with her offspring while in nestling phase is only about an hour and a half.

Since parental care is very restricted, the parents would not be able to identify their offspring without scent marking the young or the nest. If this is not done, the female may dispose of her young.

After 36 days, juveniles depart from their nest and join their parents in the other nest. Once the offspring have joined their parents in one nest they are completely weaned of their mother's milk and resemble miniature models of their parents. Parental care is still limited when the offspring have joined their parents in one nest. ("Order Scandentia", 1999; "Tree Shrews", 1985; "Tree Shrews", 2001; Martin, 1968)

Home Range

This species exhibits sexual dimorphism in home range size. The average home range of a male T. glis is reported to be 10,174 sq m, whereas for females it is 8,809 sq m. When a social unit is formed, it consists of parents and their offspring. The home range is shared and protected by all individuals of this social unit. Individuals forage independently during the day throughout the entire home range. Territories are thought to have the same boarders as the home ranges, since there is little overlap in home ranges for animals of the same sex, and fighting occurs at boarders. The social unit on each home range is modified every generation when the male offspring disperse to find their own home ranges. The females leave after the males have dispersed. The population density per hectare in common tree shrews was found to be 6 to 12 in Thailand and 2 to 5 in the Malaysia Peninsula. ("Common tree shrew (Tupaia glis)", 1995; "Order Scandentia", 1999; "Tree Shrews", 1985; Langham, 1982)

Communication and Perception

Common tree shrews have been known to use sent marking as a form of communication. They have two scent glands: one located in the sternum and the other in the abdomen. Tupaia glis rubs these glands on objects or other tree shrews. In addition to scent glands, T. glis also uses urine and feces for scent marking territories. Not only does T. glis use olfactory communication but it also uses many vocalizations in communication. Binz and Zimmermann (1989) discovered eight distinct sounds made by the genus Tupaia. When species in the genus Tupaia are even slightly disturbed a “chattering” noise is produced. It is thought that this noise might be a mob call. Varying pitches of “screams” have also been identified when the tree shrew is immediately threatened such as a deafening "squeal" which expresses aggression. Binz and Zimmerman (1989) also discovered that mating and courtship activities involve both “clucking” and “whistling” sounds. ("Tree Shrews", 1985; "Tree Shrews", 2001; Binz and Zimmermann, 1989)

Food Habits

Tupaia glis spends a majority of its time foraging for food. Its diet includes an assortment of arthropods, fruit, and leaves. Common tree shrews have even been seen eating small vertebrates! Even though T. glis is to some extent arboreal, most of the foraging occurs on the forest floor. It is often seen moving quickly in search for food in every nook and cranny of the forest understory. While in search of food, T. glis tends to use its snout for capturing its prey. The forepaws are used only for grabbing flying insects or objects just out of reach. T. glis eats very much in the same manner as a squirrel; it holds its food in its forepaws while sitting in a slouching position on its hind feet and rear. Although the foraging of T. glis is fairly general and unspecialized, tree shrews have a unique way of digesting fruit. During consumption they discard as much fiber as possible, decreasing the time of digestion. This digestive strategy is very similar to the one seen in fruit eating bats. ("Order Scandentia", 1999; "Scandentia, Tree shrews (Tupaiidae)", 2004; "Tree Shrews", 1985)

Predation

Natural predators of Tupaia glis include snakes, birds of prey, and small carnivores. In the literature there is no reference to any particular predators, however a few possible canidates are yellow throated martens (Martes flavigula), Wagler's pitviper (Tropidolaemus wagleri), red tail racers and hawks. These species could be possible predators since they all are diurnal, hunt at the same forest level that common tree shrews are found, and have been reported to prey on other arboreal, small mammals. ("Common tree shrew – Tupaia glis", 2005; John Ramsay and Kathy, 1974)

Ecosystem Roles

There is little reported in the literature on the impact that T. glis has on its environment. Some possible roles that T. glis may play in its ecosystem are as a seed disperser or population control of certain insect species.

Economic Importance for Humans: Negative

A possible negative impact T. glis may have on humans is its role as a pest in fruit plantations. However, evidence is still lacking to support the contention of common tree shrews as pests. ("Tree Shrews", 1985)

Other Comments

A very interesting and controversial subject involving tree shrews, family Tupaiidae, is their placement on the phylogenic tree. Since their discovery, tree shrews have been placed into various different orders including Afrosoricida and Macroscelididae. In the 1920s, Le Gros Clark reported similarities in musculature, brain, skull, eye development and reproductive characteristics between tree shrews and primates. Tree shrews were officially moved into the Order Primates in 1945 by Simpson’s seminal classification. In 1965, this classification was again questioned when the similarities between tree shrews and primates were determined to be either convergent because of a shared lifestyle or retained from a very early ancestor. Although some continue to classify the family Tupaiidae in the Order Primates, more commonly the family Tupaiidae resides in a separate order, Scandentia, which is thought to have characteristics of a highly developed Insectivore and a very primitive Primate. ("Order Scandentia", 1999; "Scandentia, Tree shrews (Tupaiidae)", 2004)

Contributors

Glossary

acoustic

uses sound to communicate

agricultural

living in landscapes dominated by human agriculture.

altricial

young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

arboreal

Referring to an animal that lives in trees; tree-climbing.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

chemical

uses smells or other chemicals to communicate

cryptic

having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.

delayed implantation

in mammals, a condition in which a fertilized egg reaches the uterus but delays its implantation in the uterine lining, sometimes for several months.

diurnal

active during the day, 2. lasting for one day.

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

fertilization

union of egg and spermatozoan

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

monogamous

Having one mate at a time.

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

omnivore

an animal that mainly eats all kinds of things, including plants and animals

oriental

found in the oriental region of the world. In other words, India and southeast Asia.

pheromones

chemicals released into air or water that are detected by and responded to by other animals of the same species

polygynous

having more than one female as a mate at one time

scent marks

communicates by producing scents from special gland(s) and placing them on a surface whether others can smell or taste them

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

social

associates with others of its species; forms social groups.

tactile

uses touch to communicate

terrestrial

Living on the ground.

territorial

defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

visual

uses sight to communicate

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

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The Animal Diversity Web is an educational resource written largely by and for college students. ADW doesn't cover all species in the world, nor does it include all the latest scientific information about organisms we describe. Though we edit our accounts for accuracy, we cannot guarantee all information in those accounts. While ADW staff and contributors provide references to books and websites that we believe are reputable, we cannot necessarily endorse the contents of references beyond our control.

This material is based upon work supported by the
National Science Foundation
Grants DRL 0089283, DRL 0628151, DUE 0633095, DRL 0918590, and DUE 1122742. Additional support has come from the Marisla Foundation, UM College of Literature, Science, and the Arts, Museum of Zoology, and Information and Technology Services.